The invention relates to the radiation of RF energy from a surface wave transmission line.
Because of the low-loss characteristics of surface-wave transmission lines, including Goubau lines (also called G-lines), they are the preferred transmission line when environmental conditions accommodate the unique properties of a traveling surface wave. One such application, pertinent to the present invention, is the transmission of radio frequency energy along a line towed by an aircraft such that no intermediate supports are required along the line which might interfere and cause decoupling of the surface wave energy. A prior example of this use of a G-line is disclosed in U.S. Pat. No. 3,566,317, issued to Hafner, Feb. 23, 1971, wherein RF energy launched onto an end of the line attached to the towing aircraft is efficiently transmitted to the line's distal end where all of the RF energy is recaptured by a delauncher for use in a transmitter. In another application, the RF signal energy is transmitted along the towed line, efficiently without perceptable leakage, and then at a predetermined point along the line, all of the energy is radiated outwardly from the line by a drogue radiator. The latter system is disclosed, for example, in U.S. patent application, Ser. No. 225,698, filed Jan. 16, 1981, by Buehler for "Ventriloqual-Like Jamming of Radar."